This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-267654, filed Sep. 21, 1999; and No. 11-273213, filed Sep. 27, 1999, the entire contents of which are incorporated herein by reference.
The present invention relates to a heat treating method and a heat treating apparatus.
In the manufacture of a semiconductor device or a liquid crystal device, the nonuniformity in the temperature of resist or a base substrate in heating or cooling a target substrate to be processed is reflected on the nonuniformity in the size of the pattern. Thus, with miniaturization of the pattern, the temperature control of a higher precision is required.
For example, in a post exposure baking (PEB), which is one of the manufacturing steps of a photomask, the uniformity of the temperature within a plane of a photo mask blank is very important. It was customary in the past to employ a heating method using a heater in the PEB.
However, the following problem is generated in the heater heating system. Specifically, in the normal state, a good temperature uniformity is exhibited within a plane of a photo mask blank. However, in the transition period during which the photo mask blank is being heated, a temperature distribution is derived within a plane of the photo mask blank from the low heat conductivity and the large heat capacity of the quartz substrate, giving rise to a problem that the uniformity in the pattern size within the plane of the photo mask blank is made poor.
In view of the problem noted above, a lamp heating system is being studied. However, the following problem is generated in the case of the conventional lamp heating system. Specifically, in the lamp heating system, the uniformity of illuminance is poor within a lamp irradiating region, giving rise to a temperature drop in the boundary region between adjacent lamp irradiating regions. As a result, a temperature distribution is generated in the photo resist.
Also, in the lamp heating system, it is possible to heat selectively a target thin film to be heated such as resist or a light shielding film by selecting appropriately the wavelength of the light emitted from the lamp. However, since the target thin film is heated selectively, a large temperature difference is generated between the target thin film and the quartz substrate, making it difficult to perform the temperature control with a high accuracy.
A first object of the present invention is to provide a heat treating method and a heat treating apparatus capable of making uniform the light intensity distribution caused by the light irradiation and also capable of making uniform the temperature distribution of a target substrate to be heated.
A second object of the present invention is to provide a heat treating method and a heat treating apparatus capable of performing the temperature control with a high accuracy.
According to a first aspect of the present invention, there is provided a heat treating method for heating a target substrate by means of light irradiation, wherein a light irradiation treatment is applied a plurality of times to the target substrate such that the adjacent light irradiating regions of the target substrate are allowed to partially overlap each other and that the light irradiating periods of the adjacent light irradiating regions do not overlap with each other.
In the first aspect of the present invention, it is desirable for the light irradiation treatment that is applied a plurality of times to the target substrate to be performed by changing the light irradiating regions by a predetermined order such that the adjacent light irradiating regions are allowed to partially overlap with each other.
In the first aspect of the present invention, it is desirable for the light irradiation treatment that is applied a plurality of times to the target substrate to be performed by a plurality of irradiating light generating sections arranged to conform with the light irradiating regions and arranged such that the adjacent light irradiating regions are allowed to partially overlap with each other.
In general, the light intensity in the peripheral portion of the light irradiating region is lower than that in the central portion. According to the first aspect of the present invention, it is possible to increase the light intensity in the peripheral portion (overlapping region) of the light irradiating regions so as to make the light intensity distribution uniform over the entire region of the substrate. Also, since the irradiating periods are not overlapped, the succeeding light irradiation can be performed after the temperature of the light irradiated region is lowered sufficiently. Where the light irradiating periods are allowed to overlap with each other, it is necessary to carry out a complex control in view of the effect of the heat from the adjacent light irradiating region. In the present invention, however, it is possible to suppress the effect of the heat from the adjacent light irradiating region, leading to a simple temperature control so as to make it possible to render easily the light intensity distribution uniform. It follows that, where the present invention is applied to the baking of, for example, a photo resist film, the distribution of energy imparted to the photo resist film can be made uniform, making it possible to pattern the photo resist film with a high accuracy.
According to a second aspect of the present invention, there is provided a heat treating method for heating a target substrate by irradiation with light, wherein a light irradiation treatment is applied to the target substrate such that the light irradiating regions of the target substrate do not overlap with each other, the light irradiation treatment being performed by using an irradiating light adjusted such that the distribution of the light intensity within the light irradiating region of the target substrate is rendered uniform.
In the second aspect of the present invention, it is desirable for the light irradiation treatment applied to the target substrate to be performed by changing the light irradiating regions by a predetermined order such that the light irradiating regions do not overlap with each other.
In the second aspect of the present invention, it is desirable for the light irradiation treatment applied to the target substrate to be performed by using a plurality of irradiating light generating sections arranged to conform with the light irradiating regions and arranged such that the light irradiating regions do not overlap with each other.
According to the second aspect of the present invention, used is an irradiating light adjusted to permit the light intensity distribution to be uniform and the light irradiating regions do not overlap with each other, making it possible to render the light intensity distribution uniform over the entire substrate. Also, the energy imparted to the substrate can be made uniform over the entire region of the substrate.
According to a third aspect of the present invention, there is provided a heat treating apparatus for heating a target substrate by means of light irradiation, comprising a substrate support section for supporting the target substrate, an irradiating light generating section for irradiating the light irradiating regions of the target substrate supported by the substrate support section, and a light irradiating region changing section for changing the light irradiating regions of the target substrate irradiated with the light generated from the irradiating light generating section.
According to a fourth aspect of the present invention, there is provided a heat treating apparatus for heating a target substrate by means of light irradiation, comprising a substrate support section for supporting the target substrate, a plurality of irradiating light generating sections arranged to conform with the light irradiating regions of the target substrate supported by the substrate support section and arranged such that the light irradiating regions do not overlap with each other, the irradiating light generating section generating an irradiating light adjusted to permit the light intensity distribution to be uniform within the light irradiating region of the target substrate.
According to a fifth aspect of the present invention, there is provided a heat treating method for heating a target substrate consisting of a base substrate and a thin film formed on the base substrate by a heating section, comprising the steps of detecting temperature information relating to temperature T1 of the thin film and temperature T2 of the base substrate, and controlling the heating section on the basis of temperature T1 of the thin film, temperature T2 of the base substrate, which are obtained from the temperature information, and a target temperature Ts at which the thin film is to arrive.
Where a thin film formed on a base substrate is selectively heated, a large temperature difference tends to be generated between the thin film and the base substrate. According to the fifth aspect of the present invention, the heating section is controlled in view of the temperature T2 of the base substrate in addition to the target temperature Ts and the temperature T1 of the thin film, with the result that the temperature control can be performed with a high accuracy even if there is a large temperature difference between the thin film and the base substrate.
In the fifth aspect of the present invention, it is desirable for a plurality of heating periods to be different from each other in the control characteristics of the heating section. Since the plural heating periods are made different from each other in the control characteristics, it is possible to perform the temperature control more accurately with the hunting suppressed.
Also, it is desirable for the control characteristics to be represented by a function including the temperature T1 of the thin film and the temperature T2 of the base substrate in at least one heating period.
Also, it is desirable for the control characteristics to be made different at time ta when, or before, the temperature T1 of the thin film arrives at the target temperature Ts.
Also, it is desirable to determine the time ta by estimating the time when the temperature T1 of the thin film will arrive at the target temperature TS of the thin film on the basis of the temperature T1 of the thin film and the elevation rate of the temperature T1 and by utilizing the result of the estimation.
According to a sixth aspect of the present invention, there is provided a heat treating apparatus for heating a target substrate consisting of a base substrate and a thin film formed on the base substrate, comprising a heating section for heating the target substrate, a temperature detecting section for detecting temperature information relating to temperature T1 of the thin film and temperature T2 of the base substrate, and a control section for controlling the heating section on the basis of the temperature T1 of the thin film, the temperature T2 of the base substrate, which are obtained from the temperature information detected by the temperature detecting section, and a target temperature TS at which the thin film is to arrive.
In the sixth aspect of the present invention, it is desirable for the temperature detecting section to have construction (1) or (2) given below:
(1) It is desirable for the temperature detecting section to have a first detecting section and a second detecting section each arranged on the side of that surface of the base substrate on which the thin film is formed, the first detecting section serving to detect a light having a wavelength Al that permits the temperature information of the thin film to be selectively obtained, and the second detecting section serving to detect a light having a wavelength B1 that permits the temperature information of at least the base substrate to be obtained. To be more specific, it is desirable for the first temperature detecting section to detect a light having a wavelength that is not transmitted through the thin film and for the second temperature detecting section to detect a light having a wavelength that is transmitted to some extent through the thin film and that is also transmitted to some extent through the base substrate.
(2) It is desirable for the temperature detecting section to have a first detecting section arranged on the side of a first surface of the base substrate on which the thin film is formed and a second detecting section arranged on the side of a second surface of the base substrate which is opposite to the first surface, the first detecting section serving to detect a light having a wavelength A2 that permits the temperature information of the thin film to be selectively obtained, and the second detecting section serving to detect a light having a wavelength B2 that permits the temperature information of at least the base substrate to be obtained. To be more specific, it is desirable for the first detecting section to detect a light having a wavelength that is not transmitted through the thin film, and for the second detecting section to detect a light of a wavelength that is transmitted to some extent through the base substrate.
The target substrate used in the present invention consists of, for example, a quartz substrate used as the base substrate and a photosensitive film such as a resist film and a light shielding film such as a chromium film used as the thin film.
In each of constructions (1) and (2) given above, the first temperature detecting section is arranged on the side of that surface of the base substrate on which the thin film is formed. Therefore, it is possible to obtain the temperature information of the thin film alone by setting the wavelength A1 or A2 to fall within an appropriate range. Also, in construction (1), the second temperature detecting section is arranged on the side of that surface of the base substrate on which the thin film is formed. Thus, it is possible to obtain the temperature information of the base substrate by setting the wavelength B1 to fall within an appropriate range, though the thin film is interposed between the second temperature detecting section and the base substrate. Also, in construction (2), the second temperature detecting section is arranged on the side of the second surface of the base substrate which is opposite to the first surface. Thus, the thin film is not interposed between the second temperature detecting section and the base substrate, making it possible to obtain the temperature information of the base substrate alone by setting the wavelength B2 to fall within an appropriate range.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.